The invention relates to a knee restraint device for vehicles, with a base, a knee protector component which is movable toward the knees of a vehicle occupant, a drive means which is arranged between the base and knee protector component, and limiting-and positioning means fastened to the knee protector component and the base.
A generic knee restraint device is known for example from the published European Application EP-A-0684164. The knee restraint device described there has a knee protector plate which is movable by a gas bag toward the knees of a vehicle occupant. The gas bag is able to be filled by a gas source and is arranged between the base and the knee protector plate. Limiting straps are fastened on the one side to the knee protector plate and on the other side to the base. Limiting straps and knee protector plate are provided as separate components. The limiting straps which are used consist of a polyester or nylon belt and are arranged inside the gas bag. Fastenings which are able to be torn out are provided for fastening the knee protector plate to an instrument panel in the state of rest of the knee restraint device.
A further knee restraint device is known from DE-U-29710745.
The production of a knee restraint device for vehicles is to be simplified by the invention.
According to the invention, a knee restraint device for vehicles is provided for this with a base, a knee protector component which is movable toward the knees of a vehicle occupant, a drive means which is arranged between the base and the knee protector component, and limiting-and positioning means fastened to the knee protector component and the base, in which the limiting-and positioning means have a predetermined rigidity, so that they do not undergo any change in shape at least under the influence of their own weight force, but are deformable on activation of the drive means, the limiting-and positioning means being constructed in one piece with the knee protector component. Through these measures, the production of the knee restraint device is simplified, because the alignment and fastening of the limiting-and positioning means to the base and to the knee protector component, in contrast to flexible textile bands, is easy to bring about. It is also ensured that in operation of the vehicle, no rattling or striking of the limiting-and positioning means themselves occurs. As limiting-and positioning means, for example limiting straps or guide arms can be used. The knee protector component and/or limiting-and positioning means can be produced for example from plastic or plastic injection molding, metal or metal injection molding, sheet metal, plastic/fabric composite or else metal/rubber composite. Through the construction of the limiting-and positioning means in one piece with the knee protector component, components are saved compared with knee restraint devices according to the prior art, which simplifies production and makes it cheaper. With an embodiment in a single piece, no positioning and no arranging of limiting-and positioning means against the knee protector component is necessary, a manufacturing step which requires a high degree of accuracy so as not to endanger operability of the knee restraint device.
In further development of the invention, the limiting- and positioning means have at least one limiting strap, and the at least one limiting strap and the knee protector component are produced from a single material blank. Hereby, the knee protector component and the limiting straps can be produced quickly and simply. The limiting straps and the knee protector component can be produced for example from sheet metal, plastic or else plastic with a textile insert.
Advantageously, the material blank has formed-on material tongues which form the limiting straps. After cutting the material to size, the material tongues are folded into a position necessary for the installation of the knee restraint device.
The production of the limiting- and positioning means and of the knee protector component from a single rectangular material blank is particularly advantageous, in which the limiting- and positioning means are constructed as regions of the rectangular material blank which are separated from the knee protector component by perforation lines. The shape of the sheet metal blank is further simplified thereby and the length of any sharp edges of cut which are to be machined is reduced.
As a further step, the perforation lines are formed by oblong holes. In the course of unfolding and in particular shortly before reaching the final position of the knee protector component, the material surrounding the oblong holes expands, so that these are given an approximately round shape. Thereby, for example, the stressing of the limiting- and positioning means on reaching the final position can be diminished.
It is advantageous if in the knee restraint device for vehicles, according to the invention, the limiting- and positioning means have a rigidity which is sufficient to keep the knee protector component in a position of rest. When the knee protector component is kept in a position of rest by the limiting- and positioning means, components can be saved or the production can be simplified, because no fastenings of the knee protector component which are able to be torn out are required on a rear fastening plate, for example clips or tear seams.
It is likewise advantageous that the limiting- and positioning means are plastically deformable. In this way, the knee protector component can be held in its position of rest by the limiting- and positioning means, and after activation of the drive means the knee protector component can be moved toward the occupant""s knees against the deformation resistance, to be dimensioned accordingly, of the limiting- and positioning means.
In further development of the invention, the limiting- and positioning means in the plastically deformed state have a rigidity which is sufficient to keep the knee protector component in a position reached after having protected the knees of a vehicle occupant. Also after the end of the restraint process, the knee protector component is thereby held in its final position, which presents advantages with regard to the secondary crash behavior of the knee restraint device. By an undefined position of the knee protector component after the primary crash being avoided, a damage to the lower extremities of the vehicle occupant in the secondary crash can be reduced.
Advantageously, the limiting straps are constructed as sheet metal strips and the knee protector component is constructed as a plastic plate. It is likewise advantageous when the limiting straps are constructed as sheet metal strips and the knee protector component is constructed as an aluminum plate. The fastening of the limiting straps to the base can take place for example by means of penetrating joints, welding or riveting. The fastening of the limiting straps to the plastic plate or to the aluminum plate can take place by means of penetrating joints or riveting, but also by injecting or molding during the production of the plastic or aluminum plate. By a light plastic or aluminum plate being selected, a rapid and low-delay response of the knee restraint device can be ensured. Sheet metal strips are able to be produced simply and practically without a waste of material and can be folded or bent to achieve an optimum structural space. In order to prevent damage to a gas bag serving as drive means and injuries to the occupants, the edges of the sheet metal strips can be deburred or rounded. In order to keep the limiting straps in a folded state during assembly and in the state of rest of the knee restraint device, the limiting straps can be pre-fixed in the folded state, for example by penetrating joints, welding or riveting of material layers of the limiting straps lying one over another or by penetrating joints, welding or riveting of limiting strap sections with the base and/or with the knee protector component. This prefixing is then released on activation of the knee restraint device.